linux.git/tools/perf/util/evlist.c, branch v6.7

perf evlist: Avoid frequency mode for the dummy event

2023-09-27T04:43:20+00:00

Dummy events are created with an attribute where the period and freq
are zero. evsel__config will then see the uninitialized values and
initialize them in evsel__default_freq_period. As fequency mode is
used by default the dummy event would be set to use frequency
mode. However, this has no effect on the dummy event but does cause
unnecessary timers/interrupts. Avoid this overhead by setting the
period to 1 for dummy events.

evlist__add_aux_dummy calls evlist__add_dummy then sets freq=0 and
period=1. This isn't necessary after this change and so the setting is
removed.

From Stephane:

The dummy event is not counting anything. It is used to collect mmap
records and avoid a race condition during the synthesize mmap phase of
perf record. As such, it should not cause any overhead during active
profiling. Yet, it did. Because of a bug the dummy event was
programmed as a sampling event in frequency mode. Events in that mode
incur more kernel overheads because on timer tick, the kernel has to
look at the number of samples for each event and potentially adjust
the sampling period to achieve the desired frequency. The dummy event
was therefore adding a frequency event to task and ctx contexts we may
otherwise not have any, e.g.,

  perf record -a -e cpu/event=0x3c,period=10000000/.

On each timer tick the perf_adjust_freq_unthr_context() is invoked and
if ctx->nr_freq is non-zero, then the kernel will loop over ALL the
events of the context looking for frequency mode ones. In doing, so it
locks the context, and enable/disable the PMU of each hw event. If all
the events of the context are in period mode, the kernel will have to
traverse the list for nothing incurring overhead. The overhead is
multiplied by a very large factor when this happens in a guest kernel.
There is no need for the dummy event to be in frequency mode, it does
not count anything and therefore should not cause extra overhead for
no reason.

Fixes: 5bae0250237f ("perf evlist: Introduce perf_evlist__new_dummy constructor")
Reported-by: Stephane Eranian 
Signed-off-by: Ian Rogers 
Acked-by: Adrian Hunter 
Cc: Yang Jihong 
Cc: Kan Liang 
Link: https://lore.kernel.org/r/20230916035640.1074422-1-irogers@google.com
Signed-off-by: Namhyung Kim

perf evlist: Add evlist__findnew_tracking_event() helper

2023-09-12T20:31:32+00:00

Currently, intel-bts, intel-pt, and arm-spe may add tracking event to the
evlist. We may need to search for the tracking event for some settings.

Therefore, add evlist__findnew_tracking_event() helper.

If system_wide is true, evlist__findnew_tracking_event() set the cpu map
of the evsel to all online CPUs.

Signed-off-by: Yang Jihong 
Acked-by: Adrian Hunter 
Tested-by: Ravi Bangoria 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: Anshuman Khandual 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Thomas Richter 
Link: https://lore.kernel.org/r/20230904023340.12707-3-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Free stats in all evlist destruction

2023-06-12T18:57:53+00:00

There is no evsel free stats, freeing in the evlist__delete ensures
memory leaks are avoided. Issues detected with "perf stat report" and
leak sanitizer, perf stat uses perf_session__delete to free the
evlist. Add dummy symbol for python build.

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Andi Kleen 
Cc: Athira Rajeev 
Cc: Brian Robbins 
Cc: Changbin Du 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Fangrui Song 
Cc: German Gomez 
Cc: Ingo Molnar 
Cc: Ivan Babrou 
Cc: James Clark 
Cc: Jing Zhang 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: K Prateek Nayak 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Liam Howlett 
Cc: Mark Rutland 
Cc: Miguel Ojeda 
Cc: Mike Leach 
Cc: Namhyung Kim 
Cc: Naveen N. Rao 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Sean Christopherson 
Cc: Steinar H. Gunderson 
Cc: Suzuki Poulouse 
Cc: Wenyu Liu 
Cc: Will Deacon 
Cc: Yang Jihong 
Cc: Ye Xingchen 
Cc: Yuan Can 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230608232823.4027869-14-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Reduce scope of evlist__has_hybrid

2023-05-27T12:39:51+00:00

Function is only used in printout, reduce scope to
stat-display.c. Remove the now empty evlist-hybrid.c and
evlist-hybrid.h.

Reviewed-by: Kan Liang 
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Athira Rajeev 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jing Zhang 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kajol Jain 
Cc: Kang Minchul 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Mike Leach 
Cc: Ming Wang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sandipan Das 
Cc: Sean Christopherson 
Cc: Suzuki Poulouse 
Cc: Thomas Richter 
Cc: Will Deacon 
Cc: Xing Zhengjun 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Remove evlistadd_default

2023-05-27T12:39:37+00:00

__evlist__add_default adds a cycles event to a typically empty evlist
and was extended for hybrid with evlist__add_default_hybrid, as more
than 1 PMU was necessary. Rather than have dedicated logic for the
cycles event, this change switches to parsing 'cycles:P' which will
handle wildcarding the PMUs appropriately for hybrid.

Reviewed-by: Kan Liang 
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Athira Rajeev 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jing Zhang 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kajol Jain 
Cc: Kang Minchul 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Mike Leach 
Cc: Ming Wang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sandipan Das 
Cc: Sean Christopherson 
Cc: Suzuki Poulouse 
Cc: Thomas Richter 
Cc: Will Deacon 
Cc: Xing Zhengjun 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-14-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Warn if no user requested CPUs match PMU's CPUs

2023-05-27T12:39:11+00:00

In commit 1d3351e631fc ("perf tools: Enable on a list of CPUs for hybrid")
perf on hybrid will warn if a user requested CPU doesn't match the PMU
of the given event but only for hybrid PMUs. Make the logic generic
for all PMUs and remove the hybrid logic.

Warn if a CPU is requested that isn't present/offline for events not
on the core. Warn if a CPU is requested for a core PMU, but the CPU
isn't within the cpu map of that PMU.

For example on a 16 (0-15) CPU system:
```
$ perf stat -e imc_free_running/data_read/,cycles -C 16 true
WARNING: A requested CPU in '16' is not supported by PMU 'uncore_imc_free_running_1' (CPUs 0-15) for event 'imc_free_running/data_read/'
WARNING: A requested CPU in '16' is not supported by PMU 'uncore_imc_free_running_0' (CPUs 0-15) for event 'imc_free_running/data_read/'
WARNING: A requested CPU in '16' is not supported by PMU 'cpu' (CPUs 0-15) for event 'cycles'

 Performance counter stats for 'CPU(s) 16':

    MiB  imc_free_running/data_read/
         cycles

       0.000575312 seconds time elapsed
```

Remove evlist__fix_hybrid_cpus that previously produced the warnings
and also perf_pmu__cpus_match that worked with evlist__fix_hybrid_cpus
to change CPU maps for hybrid CPUs, something that is no longer
necessary as CPU map propagation properly intersects user requested
CPUs with the core PMU's CPU map.

Reviewed-by: Kan Liang 
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Athira Rajeev 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jing Zhang 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kajol Jain 
Cc: Kang Minchul 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Mike Leach 
Cc: Ming Wang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sandipan Das 
Cc: Sean Christopherson 
Cc: Suzuki Poulouse 
Cc: Thomas Richter 
Cc: Will Deacon 
Cc: Xing Zhengjun 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-12-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Allow has_user_cpus to be set on hybrid

2023-05-27T12:38:52+00:00

Now that CPU map propagation only sets valid CPUs for core PMUs, there
is no reason to disable "has_user_cpus" for hybrid.

Reviewed-by: Kan Liang 
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Athira Rajeev 
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jing Zhang 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kajol Jain 
Cc: Kang Minchul 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Mike Leach 
Cc: Ming Wang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sandipan Das 
Cc: Sean Christopherson 
Cc: Suzuki Poulouse 
Cc: Thomas Richter 
Cc: Will Deacon 
Cc: Xing Zhengjun 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-10-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf evsel: Introduce evsel__name_is() method to check if the evsel name is equal to a given string

2023-04-24T17:28:11+00:00

This makes the logic a bit clear by avoiding the !strcmp() pattern and
also a way to intercept the pointer if we need to do extra validation on
it or to do lazy setting of evsel->name via evsel__name(evsel).

Reviewed-by: "Liang, Kan" 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/lkml/ZEGLM8VehJbS0gP2@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Use zfree() to reduce chances of use after free

2023-04-12T13:11:51+00:00

Do defensive programming by using zfree() to initialize freed pointers
to NULL, so that eventual use after free result in a NULL pointer deref
instead of more subtle behaviour.

Signed-off-by: Arnaldo Carvalho de Melo

perf util: Move perf_guest/host declarations

2023-04-10T22:22:05+00:00

The definitions are in util.c so move the declarations to match.

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Athira Rajeev 
Cc: Chengdong Li 
Cc: Denis Nikitin 
Cc: Florian Fischer 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Martin Liška 
Cc: Mathieu Poirier 
Cc: Mike Leach 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Raul Silvera 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sean Christopherson 
Cc: Suzuki Poulouse 
Cc: Will Deacon 
Cc: Xing Zhengjun 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230410162511.3055900-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo